Isolate and purify the tumor associated antigen of the MCG-7 breast cancer derived tissue culture line for use in generating heteroantisera to lead to development of a radioimmunoassay for that antigen for use in immunological testing of patients with premalignant breast disease as well as patients with clinical carcinoma of the breast. Plans for monitoring of the antigen during purification and for analysis of clinical data shall be provided to the project officer for approval before such work is underway.